Which of the following is an advantage of keeping nonnative species out of ecosystems

The answer is C, native species are more likely to survive

Explanation:

Non-native species do not co-evolve with native species which causes them to lack natural controls and predators,  which leads to unbalance in the ecosystem due to the non-native invasive species consuming resources in abundance and more effectively, allowing them to survive and reproduce more effectively than the native species.  Reduction in available resources due to competition makes it difficult for native species to survive and reproduce, leading to reduction or elimination of native species.  Therefore by not introducing non-native/invasive species, native species have a better chance of survival.

clumped distribution, because you'de have all of the population gathered in a relatively small are.

it's the most common because it provides protection and a mate for reproduction

example: humans, seeweed, cattles, etc.